This proposal relates to the study of fixation of prosthetic devices with porous materials and to the wear characteristics of artificial joints. The ability of a fiber metal composite to obtain bone ingrowth will be studied as it relates to: manufacture of the composite using titanium, and cobalt chrome alloy; the long term biocompatibility and the problem of accumulation of metallic elements locally and in distant organs; the possible carcinogenic effects of this material; the application of this material to a model of a total hip joint replacement, a surface replacement and a total knee replacement in experimental animals. Wear studies are proposed to study the characteristics and reliability of a wear resistant titanium surface and the possibility of inducing changes and improvements in the wear characteristics of UHMW polyethylene as a function of changes in its structure and physical properties.